The invention pertains to a device for twisting a coil into perforations that are provided in the margin sections of flat components, sheets of paper in particular, with a drive that causes the rotation and axial in-feed of the coil, corresponding to the inclination of its helix shape. Furthermore the invention pertains to a procedure to twist a coil into perforations that are provided in the margin section of flat components, sheets of paper in particular, in particular using a device such as the one mentioned above.
A device such as the one mentioned above is usually part of a semi or fully automatic system for the production of pads of paper that are held together with coils. In such systems sheets of paper are made of a paper web by cutting, whereupon during this production step the sheets of paper are simultaneously perforated in a margin section by means of a perforation device and imprinted in a printing machine if necessary. Afterwards these sheets of paper are overlapped and gathered into pads of a specific number of sheets of paper. Thereby the sheets of paper are stacked in such a way that the perforated margin sections are aligned to each other. The latter is important for twisting the coil through the perforations of all sheets of paper during the binding process of the paper pads in the successive binding device. The above-mentioned device and procedure are implemented in this last mentioned production step.
Such a device and procedure are for example revealed in DE 1 801 965 A1. This conventional device includes three cylinders along the length of the stack of sheets of paper to be bound. Thereby the first and second cylinders are activated and run inside a protected casing, as a third cylinder with a smooth surface acts as a supporting cylinder for the coil that is driven at the periphery. The casings that contain the first and second cylinders have two functions: (i) they have to guide the coil and (ii) hold the stack of paper sheets together between the perforations to stop them from fanning out. This known device is meant for wire coils and is constructed in a relatively complicated way.
U.S. Pat. No. 2,101,804 describes a similar device, that includes as well three cylinders that stretch out over the entire length of the book to be bound. Thereby two cylinders with concentrical, closed notches on their surface that run in peripheral direction, are activated, while a third cylinder with a smooth surface serves as supporting cylinder for the coil.
Regarding the mechanism described above the coils are first twisted into the perforations of the pre-cut layers of paper and then cut to the desired length. However, such a procedure can lead to handling problems, in particular when using plastic coils.